Description Chiefly marine and brackish, some species are catadromous. Distribution: mostly tropical and subtropical areas. Pelvic fins fused into an adhesive disc, when well developed. Spinous dorsal present or absent; when present with 2-8 flexible spines and discontinuous with soft dorsal. Cycloid or ctenoid scales almost always present. Prominent head barbels present in some. To 50 cm maximum length; most species below 10 cm. The largest family of marine fishes (possibly > 2,000). The smallest fishes in the world belong to this family. Mostly marine in shallow coastal waters and around coral reefs. Some species have symbiotic relationships with invertebrates (e.g. shrimps) and others are known to remove ecto-parasites from other fishes. Many are popular aquarium fishes. [details]